Mower suspension

ABSTRACT

A suspension system for a tractor-drawn mower used for crops for agricultural purposes is made up of parallel links, connected at a first end to a frame and to a mowing unit at a second end. A torsion spring assembly, similar to that used for torsion axles, is used to bear a portion of the weight of the mowing unit when the mowing unit is in a lower, mowing position. All torsional stress is removed from the torsion spring when the mowing unit is in a transport position. During mowing, the weight of the mowing unit is divided up between the torsion spring and the surface of the ground. The ratio of the weight supported by the ground to that supported by the torsion spring is adjustable by an operator.

TECHNICAL FIELD

The principles disclosed relate to the suspension for an agriculturalmower. More particularly, this disclosure relates to the construction ofa mower in a manner that provides a simple and cost effective productthat provides adequate suspension.

BACKGROUND

Towed agricultural mowers typically comprise a mowing unit that issupported by a frame, typically in a manner that there are two basicpositions. The first is a transport position wherein the mowing unit isin fixed position with the frame supporting its full weight. The secondis the lowered operating position wherein it is able to float, moverelative to the frame, with a portion of its weight carried by asuspension system to the frame (ultimately through the wheels to theground). The remaining portion of the weight is transferred directly tothe ground via a skid or sliding member. The weight, or forcetransferred directly to the ground via the skid is hereinafter referredto as ground pressure. The amount of ground pressure will affect theperformance of the mower. Many designs provide an operator-adjustablesuspension system. Suspension systems are designed to suspend a specificrange of weight. The weight range corresponds to a large percentage ofthe weight of the mowing unit. In this way, the desired ground pressureis provided in order to minimize damage that the skid on the mowing unitmay cause to the ground in comparison to allowing the full weight to actagainst the ground (that is, with no weight being carried on the frameand wheels).

The most common mowing units include a cutting apparatus, a cropconditioning apparatus and the drive train necessary to transfer powerto both; the total weight can be significant. Thus, the suspensionsystems require the use of elements with correspondingly significantload bearing capacity, typically relatively large extension springs.Other suspension systems utilize other types of springs, includingrubber torsion springs as disclosed in U.S. Patent Applicationspublication number 2003/0140610 to Boyko wherein a towed rotary moweruses rubber torsion elements mounted onto the frame, the rubber torsionelements supporting crank arms to support wheels and suspend the frameand mowing unit. U.S. Pat. No. 5,960,614 to Jones discloses a suspensionfor a mower that is mounted to a tractor with a frame that moves up anddown to control the height of the mower, and a suspension elementcomprising a rubber torsion axle, used to urge one of two parallellinkages in a direction to support a mower unit attached to the framewith a four bar linkage. Neither of these configurations provides anoperator control of the ground pressure.

A need thus exists for an improved suspension system for a mower thatprovides operator adjustment of ground pressure and that is adapted tooptimize the mounting onto a trailed frame.

SUMMARY

The mower unit of an agricultural crop mowing machine may be suspendedfrom a frame. The frame is supported by wheels engaging the ground. Anobject of the present invention is to provide a linkage assembly thatpermits the mowing machine to be raised into a transport position andlowered into an operating position.

A set of parallel links may be used to attach the mowing machine to theframe. The parallel links, along with a housing on the mowing machine towhich the links are attached, and the frame, comprise a parallelogramregardless of the position of the mowing machine. Therefore, the mowingmachine does not rotate relative to its frame when its position isaltered relative to the frame.

Usually, the mowing machine is partially supported by skids, wheels orthe like when it is in its operating position. Another object of thepresent invention is to provide for varying the fraction of the mowingmachine's weight that is supported on these supports. To accomplish thisobject, two link arms making up a portion of the linkage assemblymentioned above comprise torsion springs such as torsion axles used ontrailers. One end of the axle of such a torsion spring is pivotallyattached to the mowing machine. The other end of the torsion spring isrigidly attached to a link arm that is, in turn, flexibly attached tothe frame. When the mowing machine is in its upper, transport position,no torque is transferred to the torsion spring as the axle is free topivot relative to the mowing machine. As the mowing machine is loweredto its operating position, the rotation of the axle is stopped relativeto the mowing machine by a torque arm and torque is applied to thetorsion spring such that some of the mowing machine's weight issupported by the torsion spring. By adjusting the location at which theaxle's rotation is stopped relative to the mowing machine, the amount ofweight supported by the torsion spring is adjustable.

The torque arm has an aperture shaped to engage an end of the axle ofthe torsion spring. It may be turned and/or reversed by an operatorrelative to the axle and reengaged on the end of the axle to adjust theweight borne by the torsion spring when the mowing machine is in itsoperating position.

The torque arm engages a stop pin that is affixed to the mowing machine.Further adjustment to the weight borne by the torsion spring when themowing machine is in its operating position may be effected byrelocating the stop pin in angular position relative to the axis ofrotation of the torsion spring.

In another embodiment of the present invention, the torsion spring maybe pivotally attached to the frame and the link arm attached to themowing machine.

Other objects, advantages and novel features of the present inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of a trailed frame supporting a mowingunit of the present invention with the mowing unit in the raisedtransport position;

FIG. 2 is a side elevation view of a trailed frame supporting a mowingunit of the present invention with the mowing unit in a partiallylowered position;

FIG. 2 a is a detail of a portion of the side view indicated in circle 2a of FIG. 2;

FIG. 3 is a cross-sectional view taken along linc 3-3 as illustrated inFIG. 2;

FIG. 4 is an exploded isometric view of one lower link with the torsionspring from a first side;

FIG. 4 a is an isometric view of the lower link assembled from a second,or opposite side;

FIG. 5 is a side elevation view of a trailed frame supporting a mowingunit of the present invention with the mowing unit in a loweredoperating position;

FIG. 6 is a free body diagram of the mowing unit raised in a transportposition;

FIG. 7 is a free body diagram of the upper suspension link of thepresent invention raised in a transport position;

FIG. 8 is a free body diagram of the lower suspension link of thepresent invention raised in a transport position;

FIG. 9 is a free body diagram of the rubber torsion spring axle of thepresent invention raised in a transport position;

FIG. 10 is a free body diagram of the mowing unit lowered to anoperating position;

FIG. 11 is a free body diagram of the upper suspension link of thepresent invention lowered to an operating position;

FIG. 12 is a free body diagram of the lower suspension link of thepresent invention lowered to an operating position;

FIG. 13 is a free body diagram of the rubber torsion spring axle of thepresent invention lowered to an operating position; and

FIG. 14 is an isometric view of the overall machine from the rear rightside with the right side wheel removed.

DETAILED DESCRIPTION

With reference now to the various figures in which identical elementsare numbered identically throughout, a description of various exemplaryaspects of the present invention will now be provided. The preferredembodiments are shown in the drawings and described with theunderstanding that the present disclosure is to be considered anexemplification of the invention and is not intended to limit theinvention to the embodiments disclosed.

FIG. 1 illustrates a trailed mower 100 that is comprised of a frame 110supported at the rear on two tires 120, only one is illustrated as thisis a side view, and at the front by a hitch 102 of a tractor 104. Theposition of the wheels 120 is fixed in relation to the frame 110 suchthat the height of the frame 110 from the ground is fixed. In thisfigure, a mowing unit 200 is in a raised transport position, with afront side, closest to the front of the frame, configured to accept cropmaterial, and a rear side configured to eject crop material. The mowingunit 200 is mounted to the frame 110 by a linkage including parallellinks. The parallel links include two bottom links 140 a, 140 b. Theleft link 140 a is shown, while the right link 140 b is not shown.Further, the parallel links include a single top link 130, locatedbetween the two bottom links 140 a, 140 b.

In FIG. 2 this linkage is illustrated in a partially lowered positionwherein the top link 130 is connecting the mowing unit 200 to the frame110. The single top link 130 is attached to the frame 110 at a top linkframe pivot support 133, which is illustrated as approximatelyconcentric with the center of the wheels 120. This pivot support 133 canbe located in other positions, its position relative to the wheels isnot critical, and the present invention is not limited to any particularlocation for the pivot support 133. The single top link 130 is attachedto the mowing unit 200 at a top link pivot 134 by a top link ear 135.

FIG. 14 illustrates the linkage, showing both bottom links 140 a, 140 battached to the frame 110 at two frame pivots 142 a, 142 b, configuredwith pivot supports 143, on each end of the frame 110. The pivotsupports 143 of frame 110 include apertures that align to define a pivotaxis.

The bottom links 140 a, 140 b both attach on the opposite end to themowing unit 200 at two mower pivots 144 a, 144 b. The mower pivots 144a, 144 b are configured with bearings 202, 204, as will be describedbelow, as components of the mowing unit 200. The mowing unit 200 furtherincludes stops 206 that can be positioned in a variety of positions, asillustrated in FIGS. 2 a and 3.

The pivot joints at pivots 132, 134, 142 are basic pivots. Any knowntype of bearing or bushing could be employed in these pivots, preferablycomprising spherical ball joints to provide two degrees of freedom,similar to pivot 142 which includes spherical ball joint 143,illustrated in FIG. 3. The present invention incorporates a novel mowerpivot 144 including a rubber torsion axle assembly 301 (see FIG. 4).

FIGS. 4 and 4 a illustrate the arrangement of the components of themower pivot 144. The outer square tube portion 308 of a traditionalrubber torsion axle assembly 301 is fixedly connected to, and acomponent of, the lower link 140, in this embodiment configured as abolted joint. The mower pivot 144 is configured when the axle 300 isinstalled through the square tube 308, rubber springs 306 are installedin the spaces between the inside surfaces of the square tube 308 and theouter surface of the square shape of the center section of the axle 300.This rubber torsion axle assembly 301 is secured in position as theshaft portion 304 is mounted in the bearing 204, a torque arm 310 isattached to the axle portion 300 of the rubber torsion axle assembly 301and shaft portion 302 is mounted to bearing 202. The torque arm 310 isrotationally secured to the square portion of the axle portion 300 ofthe rubber torsion axle assembly 301, by the configuration of aperture311 which mates with the square tube portion of the rubber torsion axleassembly 301. An aperture 311 is constructed such that the torque arm310 is reversible, and the same component is used on both sides of themower.

FIG. 3 illustrates the torque arm 310, positioned as shown in FIG. 2 a,to come into contact with the stop pin 206 which is supported in theframe 200 and the support plate 208. After the torque arm 310 contactsthe stop pin 206, the axle 300 will be restrained from further rotationrelative to the frame 200. The mowing unit 200 can be lowered, from theposition shown in FIGS. 2 and 2 a, towards an operational positionillustrated in FIG. 5, by further extending two cylinders 150, only onecylinder 150 shown in FIG. 5. As the mowing unit 200 is thus lowered,the outer tube 308 will rotate counterclockwise, as shown in FIG. 2 a,while the axle 300 is held from rotating, causing relative rotationbetween the outer tube 308 and the axle 300, resulting in a compressionload in the rubber springs 306, generating a moment load at the mowerpivot 144.

In FIG. 1 the mowing unit 200 is illustrated raised into and held in thetransport position by the cylinder 150 that connects to the frame 110and to the lower link 140. FIG. 8 illustrates a cylinder force 152acting on one lower link 140, with a resultant force 148 a acting at themower pivot 144. A force 141 acting generally at the pivot 142 is thesum of the two other forces 148 a, 152 acting on the lower link 140.This force will result in combined distributed loading on the rubbersprings 306. The resulting equal and opposite force 148 b is applied tothe axle 300 as illustrated in FIG. 9 where an equal and opposite force248 a is applied from the mowing unit 200 through the bearings 202 and204. The free-body-diagram of FIG. 6 shows force 248 b applied to themowing unit 200. In this way, the lower links 140 transfer force fromthe cylinder to lift the mowing unit 200 with the rubber torsion axleassembly 301, while the upper link 130 holds the mowing unit 200 fromfreely rotating, via the force 136 b applied at pivot 134. The upperlink 130 will be subjected to a tensile load, as illustrated in the freebody diagram of FIG. 7.

The cylinders 150 are extended to lower the mowing unit 200 into theoperating position illustrated in FIG. 5. As the cylinders 150 extend,and the mowing unit 200 lowers, there will be rotation between both thetop link 130 and the bottom links 140 a, 140 b and their matingcomponents on both the frame 110 and the mowing unit 200. As a result ofthis rotation the torque arm 310 will move relative to the mowing unit200 from the position as illustrated in FIG. 1, to the position asillustrated in FIG. 2 a with the mowing unit 200 in a partially loweredposition. In this position the torque arm 310 will come to a positionwhere it first contacts the stop pin 206. As the cylinders 150 continueto extend, lowering the mowing unit to the position as illustrated inFIG. 5 until there is no load on the bottom links 140 a, 140 b, asprovided by a slot 152 of the cylinder 150. In addition, the loweringaction causes rotation of the bottom link 140 relative to the mowingunit 200 which will generate a torque 146 within the axle 300 resultingfrom the contact of the torque arm 310 with the stop pin 206, and areaction force 312 a. The moment 146 is the result of compression of therubber springs 306. The equal and opposite force 312 b on the mowingmachine associated with the reaction force 312 a on the torsion axle isshown in FIG. 10.

As illustrated in the free body diagram of FIG. 12, with the cylinders150 completely extended, there will be no cylinder force, and the moment146 will be applied to the end of the link 140 by the axle 300, whichwill simultaneously transmit a force 148 a. The force 148 a is theresult of unequal loading within the rubber springs 306. A force 145acting generally at the pivot 142 is the resultant due to the force 148a, and the moment 146 acting on the lower link 140. FIG. 13 illustratesthe equal and opposite force 148 b applied to the rubber torsion axleassembly 301 and torque arm 310, along with the reaction force 312 a asapplied to the torque arm. The force 248 a is applied from the mowingunit. The moment 146 is generated by a reaction force 312 a as afunction of the relative rotation at the mower pivot 144, which causescompression of the rubber springs 306. FIG. 10 illustrates a force 136 aacting at a pivot point 134, to effectively hold the mowing unit 200from rotation. The upper link 130 will be subjected to an equal andopposite tensile load, as illustrated in the free body diagram of FIG.11. The net effect of the forces applied to the mowing unit 200 is thatthe ground contact force 250 will be reduced, as a function of thetorque 146.

The torque generated within the rubber torsion axle assembly 301 is afunction of the relative rotation between the outer tube 308 and theaxle 300. This relative rotation is determined by the position at whichthe torque arm 310 first contacts the stop pin 206, and the position atwhich the mowing unit 200 contacts the ground. The pin 206 can beinserted into one of several holes as illustrated. By changing thelocation of the stop pin 206, the orientation at which the torque arm310 initially contacts the stop pin 206 is modified. This modificationaffects the relative rotation the axle 300 is subjected to. Thus, byadjusting the position of the stop pin 206, while the mowing unit 200 isin its raised position, as illustrated in FIG. 1, the amount of torquegenerated by the axle 300 when the mowing unit 200 is lowered to theoperating position, as illustrated in FIG. 5, is controlled. Thisadjustment allows the operator to adjust the lift force and thus theresulting ground pressure.

The above embodiment is the preferred embodiment, but this invention isnot limited thereto. It is, therefore, apparent that many modificationsand variations of the present invention are possible in light of theabove teachings. It is, therefore, to be understood that within thescope of the appended claims, the invention may be practiced otherwisethan as specifically described.

1-6. (canceled)
 7. A method of suspending an agricultural implement froma frame, said frame being operatively supported on a ground surface andsaid agricultural implement being free to move at least in a verticaldirection independent of the frame, the method comprising the steps of:(a) operatively attaching a first end of a torsion spring to theagricultural implement, said agricultural implement in suspensionrelative to the frame; (b) operatively attaching a second end of thetorsion spring to the frame; (c) orienting the torsion spring such thatno torque is applied to the torsion spring due to a weight of theagricultural implement when said agricultural implement is in atransport position; and (d) positioning the torsion spring such that atleast a portion of the weight of the agricultural implement is borne bythe torsion spring when the agricultural implement is in an operatingposition.
 8. The method of claim 7 wherein the operating position of theagricultural implement is lower than the transport position.
 9. Themethod of claim 7 including the step of transferring the agriculturalimplement between the transport position and the operating position byactuating a hydraulic cylinder.
 10. The method of claim 7 additionallycomprising the steps of: (a) operatively attaching a first end of atleast one link arm to the frame; (b) operatively attaching a second endof the at least one link arm to the agricultural implement; and (c)mounting at least one additional link arm parallel to the at least onelink arm.
 11. The method of claim 10 additionally comprising the stepsof: (a) operatively attaching a first end of the additional at least onelink arm to the frame such that an axis of rotation of the first end ofthe additional at least one link arm relative to the frame is notcollinear with an axis of rotation of the first end of the at least onelink arm relative to the frame; and (b) operatively attaching a secondend of the additional at least one link arm to the torsion spring suchthat an axis of rotation of the first end of the additional at least onelink arm relative to the agricultural implement is not collinear with anaxis of rotation of the first end of the at least one link arm relativeto the agricultural implement.
 12. An apparatus for operativelysuspending an agricultural implement from a frame, said apparatuscomprising at least one torsion spring, a first end of the torsionspring being operatively attached to the frame, a second end of thetorsion spring being operatively attached to the agricultural implement,said torsion spring oriented to support at least a portion of a weightof the agricultural implement when said agricultural implement is in anoperating position and to support none of the weight of the agriculturalimplement when said agricultural implement is in a transport position.13. The apparatus of claim 12 additionally comprising at least one toplink comprising two ends, a first end operatively, pivotally attached tothe agricultural implement and a second end operatively, pivotallyattached to the frame.
 14. The apparatus of claim 13 additionallycomprising a link arm, a first end of the link arm operatively attachedto the torsion spring, a second end of the link arm operatively attachedto the agricultural implement.
 15. The apparatus of claim 12 wherein thetorsion spring comprises: (a) an outer tube, substantially rectangularin cross section; (b) a torsion axle, substantially rectangular in crosssection and inserted inside the outer tube such that space remainsbetween the torsion axle and inside surfaces of the outer tube; and (c)at least one rubber spring installed in the space between the insidesurfaces of the outer tube and the torsion axle.
 16. The apparatus ofclaim 15 additionally comprising a torque arm, the torque armcomprising: (a) an aperture that engages an end of the torsion axle, theaperture shaped to permit the torque arm to permit adjustment of theposition of the torque arm to a plurality of positions on the torsionaxle; and (b) a lever arm for halting a rotation of the torsion axle bycontacting a stop pin.
 17. The apparatus of claim 16 wherein theaperture is also shaped to be reversible on the torque arm.
 18. Theapparatus of claim 16 wherein an angular location of the stop pin aroundan axis of rotation of the torsion axle is adjustable.
 19. The apparatusof claim 15 additionally comprising a bearing on which an end of thetorsion axle rotates.
 20. The apparatus of claim 12 additionallycomprising an actuator for raising and lowering the agriculturalimplement relative to the frame.
 21. The apparatus of claim 20 whereinthe actuator is a hydraulic cylinder.
 22. The apparatus of claim 20additionally comprising: (a) an actuator shaft; and (b) a slottedactuator shaft end to which the agricultural implement is operativelyattached, the slotted end providing for vertical movement of theagricultural implement while said agricultural implement is in itsoperating position.
 23. The apparatus of claim 12 wherein theagricultural implement is a mower.
 24. A method of suspending anagricultural implement from a frame, ground engaging wheels beingoperatively, rotatably attached to said frame, said agriculturalimplement being free to move at least in a vertical direction relativeto the frame, the method comprising the steps of: (a) operatively,pivotally attaching a first end of a first link arm to the agriculturalimplement at a first pivotal attachment; (b) operatively, pivotallyattaching a first end of a second link arm to the agricultural implementat a second pivotal attachment, wherein the second pivotal attachment isvertically disposed from the first pivotal attachment; (c) operatively,pivotally attaching a second end of the first link arm to the frame at athird pivotal attachment comprising a torsion axle; (d) operatively,pivotally attaching a second end of the second link arm to the frame ata fourth pivotal attachment, wherein the fourth pivotal attachment isvertically disposed from the first pivotal attachment; (e) operatively,pivotally attaching a first end of a linear actuator to the frame; (f)operatively, pivotally attaching a second end of the linear actuator toone link arm selected from the group consisting of the first link armand the second link arm; (g) arranging said first link arm and saidsecond link arm to be parallel in all positions; and (h) supporting atleast some of a weight of the agricultural implement with the torsionaxle.